The wireless access box is a kind of wireless access terminal, connected with the telephone through the interface (such as the RJ11 interface) offered by the user interface circuit, can realize the wireless access service of each operator in the world by adopting various systems, and realizes the voice communication within the cover range of the wireless network.
On the current router or the Ethernet switchboard, there is a transmission interface through which it can be realized that routers or switchboards are interconnected and used at the same time. In these interfaces of the current devices, it generally adopts the E1 interface of the European system and the T1 interface of North American, etc., and these interfaces have different impedance types. Wherein, the E1 interface usually supports the peripheral with 120 ohms and 75 ohms impedance, and the T1 interface supports the peripheral of 100 ohms. While the telephones used by the users of each country are different, their internal impedances are divided into these 3 different kinds too, and the impedance matching of the wireless access box and the telephone becomes a problem.
At present, there is a kind of solution directed at the three kinds of impedance standards of the E1 and T1 interface, which changes the parameters of the interface circuit board of the wireless access box, and selects different impedances to match separately. Each kind of interface mode corresponds to a kind of interface circuit board separately, and it needs to design three kinds of interface circuit boards with different impedances to be able to meet the delivery demand of various areas. The kind of solution has at least two shortcomings: increasing the interface circuit board additionally, and increasing the design cost; various types of the interface circuit boards, and inflexible product configuration management.
Another solution is configuration by hand, that is, designing a toggle switch on the wireless access box mother board, and selecting different impedance modes by turning the toggle switch. This solution also has several shortcomings, which are as follows:
(1), in order to realize matching of the three kinds of impedance modes, it needs to design at least a 4-way toggle switch, which not only causes that the appearance of the wireless access box increases the position of the toggle switch, but also the toggle switch itself costs high, the area of the mother board PCB of the wireless access box is increased additionally, and the cost is increased doubly;
(2), the practical operation is complex, and additional instruction is needed for the usage by the user, otherwise the artificial fault operation appears easily;
(3), it contacts by using the metal spring within the toggle switch, and it is easy to cause the metal spring to wear out and then cause the poor contact after the numerous operations for a long time, and the reliability is not good.